1. Field of the Invention
The present invention relates to an information processing method, apparatus, and computer readable medium, and more particularly relates to an information processing method, apparatus, and computer readable medium having stored therein a program capable of moving a manipulator to an object quickly, accurately, and stably as a control system.
2. Related Art
Conventionally, robot arms equipped with a manipulator are arranged in the production lines of automobiles and the like, and perform bolt tightening operations when assembling a work such as an automobile door. Specifically, the robot arm performs operations of selecting a bolt hole on which to perform subsequent bolt tightening from among a plurality of bolt holes formed in a surface of the work as an object, moving up to the object, and inserting and threading a bolt thereinto.
As control to cause the robot arm to move up to the object, teaching playback control that causes the robot arm to move along a path set in advance up to a target position, with a position (hereinafter referred to as “taught position” set in advance based on the position of the object defined as the target position, is widely employed. Teaching playback control indicates open-loop control which teaches beforehand an operation to cause the robot arm to move along a predetermined path set in advance, and causes this operation to be repeated.
However, in actual operation, misalignments in the position or attitude of the work occur attributed to the stopping accuracy of work conveyance on the production line, individual variability of the work pallets for conveying works on the production line, or the like. Due to these misalignments, error arises between the taught position and the actual position of bolt holes.
Consequently, in order to eliminate such error, Japanese Unexamined Patent Application, Publication Nos. H8-174457 and 2001-246582 disclose methods of acquiring the deviation between a position of a tip end of the robot arm and the actual position of the bolt hole, by way of a camera attached to the tip end of the robot arm, and correcting the position of the robot arm based on the deviation. In this position correction, predetermined feedback control using a value based on the deviation as a feedback value, e.g., PID control, is employed.